>>The statists are afraid of technology, especially 3D printing. <<
When 3D printing is criminal only 2D people will print...
(or something similar)
If the technology is in circulation there will be no way for a government to effectively stop this with the possible exception of controls upon the propellant (gun powder)
Even now you can with a few rather basic metal working tools - lath, drill press, saw, riveter and welder - create a fully functional AK-47 clone in your garage workshop. If you can print the parts from a high density polymer then any restrictions on the availability of firearms are simply gone.